Of Fe <sub> 2 </ Sub> The O <sub> 3 </ Sub> Preparation Of Nanoparticles And Nanorods

The preparation and application of γ-Fe2O3 nano-particles are currently attracting considerable attention because of their excellent ferromagnetic properties. And the morphology and size of particles are important factors to influence their performance. Thereby it is still significant to find new preparation methods of γ-Fe2O3 nano-particles.Nanoscale one-dimensional structures have attracted many people to research because of their unique electric, optical, and mechanical properties as a result of their low dimensionality, which also results in their potential applications in nanodevices and microsensors. Thereby a number of recent studies have been focused on the preparation and research of properties of nanoscale one-dimensional structures. Iron oxides are widely used as semiconductor , recording materials and photocatalyst. Nanostructured Fe2O3 thin films and particles have been prepared, and little work exists for Fe2O3 nanorods or nanowires.In this thesis, γ-Fe2O3 nano-particles were prepared by using simple (wet)solid -phase grinding method. And different morphological γ-Fe2O3 nano-particles were prepared by using solution reaction-calcining method. By adding one kind of surfactant and resultant calcining of precursors, α-Fe2O3 nanorods were synthesized. The resultant samples were characterized by XRD,Mossbauer Spectroscopy, TEM, TG-DTA, FTIR and the preparation process was also studied.The main results are as follow:In the presence of polyethylene glycol(PEG-400), the mixture of FeCl3·6H2O and NaOH was grounded and the γ-Fc2O3 nanoparticles were prepared. The product obtained was washed and dried at 60℃ and calcined at different temperatures for Ih. XRD. Mossbauer Spectroscopy, TEM, TG-DTA and FTIR were used to characterize the samples. The results show that after dried at 60℃ for 2h, the as-grounded sample was transformed into poor-crystalline γ-Fe2O3 ultrafine powder. After being calcined at450℃ for 1h,the ultrafine powder became good crystalline γ-Fe2O3 nanoparticles with particle size of 30nm. After being calcined at 500℃ for 1h, perfect-crystalline γ-Fe2O3 nanoparticles were gotten with particle size of 40nm.When FeCl3 and NaOH react, if PEG added and the resultant deposit not being washed, the rod-like γ-Fe2O3 nanoparticles were gotten with aspet ratio at ca.6, length ca.200nm, width ca.30nm,otherwise the cubic-like γ-Fe2O3 nanoparticles were gotten with particle diameter at about 20nm. We found the loading amount of PEG affects the composition and morphology of particles. When the loading amount of PEG is 2ml/60mIH20, the particle size of γ-Fe2O3 by calcining of sample at 300℃ is minimum, thereby the loading amount of PEG 2ml/60mlH2O is optimal.By adding surfactants-sodium dodecyl sulphate(SDS) , TritonX-100 and CTAB into the solution of FeSO4- NH4Ac, we studied their effect on the morphology of precursor. No effect on the morphology of precursor was observed for TritonX-100 and CTAB, but the addition of SDS progressed the particle growth and the aspect ratio(25) of particles is maximum when [SDS/Fe] is 0.15(the sample marked as NR4). After NR4 was calcined at 500℃ α-Fe2O3 nanorods were gotten with aspect ratio at about 15-20 (length 500-600nm,width 30nm)...